The fatigue prone structures made of carbon fiber reinforced polymer composites (CFRPCs) are frequently used in aerospace, defense, structural, and automotive applications. In this work, a novel method was reported that increases the fatigue life of CFRPC (96.56% at an average) by interface strengthening. The fatigue life of CFRPC composite was evaluated using the standard bending cyclic fatigue test. The CFRPCs were prepared by the hand layup method using a specially designed compression molding setup. The waste glass powder and PVA adhesive were used for treating the carbon fibers (CFs). The statistical analysis was used to interpret the effect of the volume fraction variation of the treated/untreated CFs on the cyclic fatigue strength (CFS) of the CFRPC. The effect of treatment and the load ration (R) on CFS of CFRPC were reported. The finite element (FE) model was developed using the transient analysis in COMSOL multi-physics (Explicit Dynamics Module) to obtain the deformation and stresses for treated/untreated CFRPC made using single tow of the carbon fiber. The experimentation on treated and untreated single tow CFRPC was performed to validate and complement the FE model. The stress-deformation-life relations for CFRPC were established. The scanning electron microscopy (SEM) images were used to establish the structure-property relationship and explain the basis for increment in CFS of CFRPC. Analysis of variance was conducted to ensure the validity of the experimental results.

Novel method for improving fatigue behavior of carbon fiber reinforced epoxy composite

The use of natural fiber composites in the fatigue prone structures is limited due to the lower strength and durability when compared to the carbon fiber reinforced polymer composites. The present work focuses on improving the bending cyclic fatigue strength (CFS) of the sugarcane fiber reinforced epoxy composite (SFRPC) by a novel treatment method. The treatment has increased up to 40% fatigue life of SFRPC by fiber and interface strengthening. The fatigue life was evaluated using the standard bending cyclic fatigue test. The SFRPCs were prepared using a specially designed compression molding setup by the hand layup method. The sugar cane fibers (SCF) were treated using the waste glass powder and PVA adhesive. The statistical analysis was conducted to observe the effect of the treatment method, the load ration (R) on CFS of treated/untreated SFRPC. A comparison of CFS of SFRPC (treated/untreated) with CFRPC is presented based on the author's previous work. A finite element based model was constituted for predicting the elastic properties of SFRPC (treated/untreated) at different fiber proportions. Additionally, a finite element (FE) model was constituted using the transient analysis in ANSYS (Explicit Dynamics Module) for obtaining the deformation and Von Mises stress at different R for the corresponding life of the treated/untreated SFRPC sample. A theoretical explanation for improved fatigue behavior of SFRPC was presented using scanning electron microscopy (SEM) micrographs and FE results collectively. The stress-strain-life relations for treated/untreated SFRPC were established. It was found that the shear yielding resulted due to the fracture of the outer glass layer of the SCF resulted in the higher CFS of the treated SERPC.

Modeling improved fatigue behavior of sugarcane fiber reinforced epoxy composite using novel treatment method

https://iopscience.iop.org/article/10.1088/2053-1591/ab3ac0/pdf

Improving fatigue behavior of cow-dung fiber reinforced epoxy composite using waste glass powder

Preparation and characterization of Mechanical Properties of Epoxy Resin Composites reinforced with Non Bio-degradable Wastes

Epoxy resin was filled with sawdust to optimize the flexural properties of the composite for structural applications. In order to reduce costs, it will be necessary to fill as much sawdust as possible subject to maintaining sufficient strength of the composites in civil and structural applications. This project varies the percentage by weight of the sawdust in the composites. The sawdust particles were sieved into three different sizes, which were <425 mm, 425–600 mm and 600–1180 mm, respectively. Palm oil was also added to the composites of epoxy resin and sawdust as a plasticizer to improve the flexibility of the composites. After casting the composites to the moulds, they were cured at ambient conditions for 24 h. They were then post-cured in a conventional oven or microwave irradiation and subjected to flexural tests. It was found that the best percentage of sawdust, with particle size of <425 mm, and of palm oil, by weight that can be added to epoxy resin to give an optimum flexural modulus and flexural strength, as well as cost was 15% and 5%, respectively. The contribution of the study was that if flexural modulus was the most important factor to be considered in the applications of the composites, sawdust is a suitable filler. However, if the most sought after properties were the flexural strength then sawdust is not a suitable filler.

Flexural properties of sawdust-reinforced epoxy composites post-cured in microwaves

Epoxy resin was filled with glass powder to optimize the strength and of the composite for structural applications by a research centre in the University of Southern Queensland (USQ). In order to reduce costs, the centre wishes to fill as much glass microspheres as possible subject to maintaining sufficient strength and fracture toughness of the composites in structural applications. This project varies the percentage by weight of the glass powder in the composites. After casting the composites to the moulds, they were cured at ambient conditions for 24 hours. They were then post-cured in a conventional oven and subjected to tensile tests. It was found that the best percentage of glass powder by weight that can be added to the epoxy resin to give an optimum yield and tensile strengths as well as Young modulus and cost was five percent. It was also found that the fractured surfaces examined under scanning electron microscope were correlated with the fracture toughness. The contribution of the study was that if tensile properties were the most important factors to be considered in the applications of the composites, glass powder is not a suitable filler. It is also hoped that the discussion and results in this work would not only contribute towards the development of glass powder reinforced epoxy composites with better material properties, but also useful for the investigations of tensile properties in other composites.

/pdf/tensile-tests-of-glass-powder-reinforced-epoxy-composites-axr1ryq5g2.pdf

H. Fung

Papers

Tensile Tests of Glass Powder Reinforced Epoxy Composites: Pilot Study